design of journal bearing test rig - rochester institute...
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Master's Degree Thesis ISRN: BTH-AMT-EX--2012/D-16--SE
Supervisors: Ansel Berghuvud, BTH
Department of Mechanical Engineering Blekinge Institute of Technology
Karlskrona, Sweden
2012
Raajeshkrishna R. Govindaraj
Vikrant Mehamala Satishkumar
Design of Journal Bearing Test Rig
2
Design of
Journal Bearing Test Rig
Raajeshkrishna R. Govindaraj
Vikrant Mehamala Satishkumar
Department of Mechanical Engineering
Blekinge Institute of Technology
Karlskrona, Sweden
2012
Thesis submitted for completion of Master of Science in Mechanical
Engineering with emphasis on Structural Mechanics at the Department
of Mechanical Engineering, Blekinge Institute of Technology,
Karlskrona, Sweden.
Abstract:
Our study deals with a design of suitable test rig, which can help in
determining the load bearing capacity, pressure distribution of a journal
bearing. Present project work is about designing a test rig, which can be
further utilized to check on the behavior of different materials as may be
proposed in the design of journal bearing. Therefore the study involves
theoretical aspects on the working principle of a journal bearing,
numerical calculation and finally a 3D model of the test rig. The sole
purpose of designing a test rig is to make it an economical design and
yet fulfilling its purpose for conducting experiments. Realization of the
project is achieved through 3D modeling and 2D drawing using
Autodesk inventor. Test rig will allow the end user to visualize the
behavior of any bearing under different working conditions.
Keywords:
Journal bearing, Eccentricity, 3-D modeling, Pressure distribution
3
Acknowledgements
This work has been carried out under the supervision of Dr. Ansel
Berghuvud at the department of Mechanical Engineering, Blekinge Institute
of Technology, karlskrona, Sweden.
We express our deep sense of gratitude to our Supervisor, Dr. Ansel
Berghuvud for his guidance in our each steps and providing abundant
knowledge and experience throughout the study.
We thank Mr. M.S. Satishkumar for is valuable feedback in carrying out
the project work.
We thank our beloved friend Saravanan Dasarathan for helping us out in
computer diagrams.
Finally we would like to thank our family and friends for their continuous
support and encouragement to compete our master’s studies.
Karlskrona
September 2012
Raajeshkrishna R.Govindaraj
Vikrant Mehamala Satishkumar
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Contents
1 Notations ........................................................................................... 7
2 Introduction ...................................................................................... 8
2.1 Statement of the thesis work ........................................................... 9
2.2 Specified aim and purpose of the work .......................................... 9
3 Theoretical Background ................................................................ 10
3.1 Basics of bearings ......................................................................... 10
3.2 Classification of bearings ............................................................. 10
3.3 Basic Principle of Journal Bearings ............................................. 10
3.4 Working Principle of Journal Bearing .......................................... 11
4 Analytical Method .......................................................................... 13
4.1 Assumptions ................................................................................. 13
4.3 Feasible model .............................................................................. 13
4.4 Determination of pressure distribution ......................................... 13
4.4.1 Assumptions .......................................................................... 14
4.5 Pressure distribution for varying angles ....................................... 15
5 Product Development ..................................................................... 18
5.1 Design Approach .......................................................................... 18
5.1.1 Phase 1 .................................................................................. 18
5.1.2 Phase 2 .................................................................................. 18
5.1.3 Phase 3 .................................................................................. 19
5.2 Manufacturing parts ...................................................................... 19
5.3 Parts to be procured ...................................................................... 19
5.3.1 Procurement parts .................................................................. 20
6 Design of individual parts .............................................................. 21
6.1 Bearing ......................................................................................... 21
5
6.1.1 Design need ........................................................................... 21
6.1.2 Dimension and specification ...................................................... 21
6.2 Journal shaft ................................................................................. 23
6.2.1 Design need ........................................................................... 23
6.2.2 Dimension and specification ................................................. 23
6.2.3 Design motivation ................................................................. 23
6.3 Base plate ..................................................................................... 24
6.3.1 Design need ........................................................................... 24
6.3.2 Dimension and specification ................................................. 25
6.3.3 Design motivation ................................................................. 25
6.4 Frame ............................................................................................ 26
6.4.1 Design need ........................................................................... 26
6.4.2 Dimension and specification ................................................. 27
6.4.3 Design motivation ...................................................................... 27
6.5 Weight holder ............................................................................... 29
6.5.1 Design need ........................................................................... 29
6.6 Copper tubes ................................................................................. 29
6.6.1 Design need ........................................................................... 29
6.6.2 Dimension and specification ...................................................... 30
6.7 Oil tank ......................................................................................... 30
7 Assembly process ........................................................................... 31
7.1 Assembly chart ............................................................................. 33
7.2 Assembly Steps ............................................................................ 34
8 Experimental approach ................................................................ 35
8.1 Working principle ........................................................................ 35
8.2 Calculation of pressure head ........................................................ 36
9 Cost Estimation .............................................................................. 37
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10 Conclusion ....................................................................................... 39
11 Future work .................................................................................... 40
12 References ....................................................................................... 41
Appendix ................................................................................................. 44
Bearing .................................................................................................... 44
Shaft ......................................................................................................... 45
Weight holder .......................................................................................... 46
Assembly ................................................................................................. 47
Support block ........................................................................................... 48
Frame 1 .................................................................................................... 49
Frame 2 .................................................................................................... 50
7
1 Notations
C Clearance of the bearing
e eccentricity of the bearing
ε eccentricity ratio
Θ Angle
Pmax maximum pressure
R radius of the shaft
µ Viscosity of the lubricant
U velocity of the shaft
8
2 Introduction
Journal bearing is the most common type of plain bearing. It consists of a
sleeve, with a shaft rotating in it and a thin film of lubricant, restricting the
contact between them. The study on journal bearing comes under
Engineering Tribology. As known, small improvements in the field of
Tribology leads to better usage of energy [2]. Importance lies in testing
newly found material such as the polymers, to see whether they are suitable
for bearing application.
A test rig is an apparatus or equipment used for measuring the performance
of any mechanical equipment. Test rig can be placed in laboratory for
studying the pressure distribution of the journal bearing.
Journal bearings play an important role in almost every automobile
application. The bearing guiding the shaft should have good thermal
properties, strength and load bearing capacity. The friction between bearing
and shaft should be low in order to get good power transmission. The direct
contact between the shaft and the sleeve should be avoided, since it will
damage both the sleeve and shaft. The lubricant will form a thin film
between the moving surfaces. The pressure build-up varies according to the
load in the bearing. Higher load in the bearing, results in direct contact with
the shaft and the sleeve, which will damage both surfaces. The maximum
pressure for every bearing should be determined so that it does not exceed
the limits under any working condition, in order to avoid damage to the
bearing.
In this present work, laboratory equipment was developed to determine the
maximum pressure in the journal bearing, under certain load conditions.
The set up has some design constraints like flexibility, so that it could be
fixed in any laboratory, without disturbing the alignment of the shaft and
motor. Also the rig should be mobile, so that it can be transported or moved
to any location. Initially an analytical calculation was carried out, in order to determine the
pressure distribution with necessary assumptions. Then further on, the
design of parts for the whole setup. While choosing some parts in the setup
like plumber block, materials for bearings, shafts, tubes and the selection of
motor for the desired RPM, standard dimensional parameters and standard
equipments were considered for the setup.
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2.1 Statement of the thesis work
The work involves developing laboratory equipment for the purpose of
testing journal bearing materials. This equipment will be used at a
laboratory to analyze different bearing material types that can be used for
manufacturing bearings.
The work involves a coordinated approach between theoretical calculation
and iterative steps to design and develop comprehensive and feasible setup
for the purpose of testing journal bearing materials.
2.2 Specified aim and purpose of the work
The main aim of the thesis is to design test rig, journal bearing and shaft
with certain clearance set up of the system provision for taking out line to
measuring board. To know how pressure is developed at different points in
the journal bearing. By applying loads the proportional pressure is also to
analyse the design of compact and portable equipment is done using CAD
modelling software such as Autodesk Inventor. Determine the cost of the
product and study feasibility of the whole design.
2.3 Background
Numerous types of experiments have been conducted on bearings and the
studies continue, with advancements in technology and materials, resulting
in need for analysis of these new materials suitable for bearing application.
Journal bearings test rig used for this educational purpose was built
specifically to our laboratory. A 3D model is made using the software
AUTODESK INVENTOR.
10
3 Theoretical Background
3.1 Basics of bearings
As known, bearings have played a vital role in engineering. The main
purpose of a bearing is to support a rotating shaft or play as intermediate
between a rotating part and a stationary part.
3.2 Classification of bearings
Bearings can be classified as hydrodynamic and hydrostatic bearings. In
hydrodynamic bearings, the lubricant is absorbed or forced into the system
by the rotation of the bearing. Whereas in a hydrostatic bearing system, an
external source like a pump is required to force the lubricant into the
system [16].
Journal bearings are mainly used for carrying axial loads or vertical loads.
Journal bearing is a hydrodynamic bearing where, due to rotation of the
journal in the bearing the lubricant is forced into the system. The bearing
has a rotating shaft guided by a bearing, which is fixed. The friction
between bearing and shaft is reduced by means of lubricants with high
viscosity. The lubricant flows between the shaft and the stationary bearing.
When the bearing is in running condition, there will be a pressure build up
between the shaft and the bearing. The pressure should be tested for better
performance and increased durability of the bearing.
3.3 Basic Principle of Journal Bearings
Journal bearing also called as plain bearings are widely used in automobile
applications, not restricting the smooth movement of the parts. Journal
bearings consist of two parts, the shaft transmitting the motion also known
as the journal and the sleeve guiding the shaft. Both the parts are made of
specific metal with good thermal properties and strength. The friction
between two parts should be less in order to deliver the transmission with
good efficiency. A thin film of lubricant is present between the two metal
surfaces to prevent the direct contact between them also reducing friction.
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The direct contact between metals may lead to damage of the shaft, or the
sleeve leading to failure of the mechanism.
Load to the journal bearing can be of two types. Load applied on the shaft
and load applied on the sleeve depending on the working conditions and
type of applications used. In our case we are dealing with hydrodynamic
bearing with load applied on the sleeve. Since the load is applied on the
sleeve, the gap between the top layer of the shaft and the sleeve will be
reduced forming a converging surface at the top, which on rotation of the
shaft develops pressure inside the bearing. The aim of this project is to
calculate the pressure inside the bearing [16].
3.4 Working Principle of Journal Bearing
Depending upon the type of application the two cases of journal bearing
can be considered.
The journal shaft can be fixed and the sleeve can move perpendicular to the
axis of the shaft. That is the sleeve can be self-positioning.
The sleeve can be fixed and the journal shaft can be self-positing depending
upon the load type.
Irrespective of the type of application in a journal bearing, the position of
the journal or the sleeve is directly related to the external load. When the
bearing is sufficiently supplied with lubrication and under zero loads, the
journal shaft or sleeve will rotate concentrically within the bearing. When a
load is applied the journal or sleeve moves eccentric position forming a
wedge shape of oil film, where the load supporting pressure is generated.
The clearance will be of the order of one thousandth of the diameter of
journal. The figure below depicts the different parts and also the terms used
in the journal bearing
12
Figure 3.1. Journal bearing.
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4 Analytical Method
As any mechanical project starts with a mathematical calculation, in present
project it is important to know the pressure distribution on the bearing
surface. Pressure distribution and maximum pressure in bearings vary
according to load on the bearing, speed of the shaft and materials used.
Initially for mathematical calculations dimensions of the bearing, load, and
velocity of the shaft are assumed for calculating the maximum pressure in
the bearing.
4.1 Assumptions
The pressure and viscosity are both considered to be constant through the
length of the bearing [2].
Derivative of velocity across the film thickness are far more important than
any other velocity derivatives
The flow is laminar
The lubricant is considered to be Newtonian
The lubricant adheres perfectly to the surfaces of the solids
End leakage is negligible.
4.3 Feasible model
Considering short bearing type of equation for this experiment; henceforth
a bearing of diameter to length ration almost equivalent to 1 is chosen.
Therefore 100 x 100 mm bearing is considered for this purpose. This size is
good enough to manufacture and also for experimental purpose.
4.4 Determination of pressure distribution
Eccentricity: The distance between the center axis of the shaft and the
sleeve.
14
Eccentricity ratio: It is the ratio of radius of shaft to clearance in the
bearing.
The distance between the center part of the shaft and the center part of the
sleeve is called the eccentricity. Eccentricity plays a key role in varying the
pressure in the bearing. Varying pressure is directly proportional to varying
eccentricity. The maximum possible eccentricity is the radial clearance of
the bearing. So the ratio of eccentricity to the clearance gives the
eccentricity ratio. Eccentricity ratio can vary from 0 to 1. If the ratio is zero,
then the shaft is exactly in the center of the bearing sleeve. Also this
indicates that there is no pressure and in the bearing. And if the eccentricity
ratio is one, then the load on the bearing is maximum and there is contact
between the shaft and the sleeve. By varied the eccentricity ratio from 0 to
1 for pressure calculation. So our pressure calculation is preceded with the
Reynolds’s equation as its base [3], [4]. So the equation for calculating the
maximum pressure is,
4.4.1 Assumptions
µ=0.01 Ns/m2, viscosity of the lubricant.
U=10 m/s, velocity of the shaft.
r=50 mm, radius of the shaft.
Θ=0-180 .
c=40 µm, clearance of the bearing for minimum tolerances.
c = 130 µm, clearance of the bearing for maximum tolerances.
e= eccentricity of the bearing.
ε=0.1, eccentricity ratio.
15
Figure 4.1. Shaft and sleeve tolerance.
Here a tolerance range of 40 to 130µm has been chosen, to get a pressure
distribution in a range of 0.1 to 0.4 bars, which is equivalent to a weight of
5kgs to 20kgs. This weight range is ideal for laboratory usage.
Substituting the above mentioned assumptions in the Reynolds’s equation
gives,
4.5 Pressure distribution for varying angles
By varying the rollup angle from 0 to 180 and calculated the relative
pressure in the bearing. The pressure distribution for maximum and
minimum tolerance has been tabulated in the following table.
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Table 4.1. Pressure distribution for with minimum and maximum tolerances
varying roll-up angles.
Angle, Degrees Pressure, *103N/m
2
Maximum tolerance
Pressure,*104 N/m
2
Minimum tolerance
0 0
0
20 0.5980*103
0.6414*104
40 1.124*103 1.2058*10
4
60 1.5145*103 1.6247*10
4
80 1.7224*103 1.8478*10
4
100 1.7227*103 1.8480*10
4
120 1.5151*103 1.6253*10
4
140 1.1246*103 1.2065*10
4
160 0.5984*103 0.6420*10
4
Figure 4.2. Pressure Distribution for Maximum and minimum tolerances
for different roll-up angles.
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Figure 4.3. Pressure Distribution for Maximum and minimum tolerances
for different roll-up angles with eccentricity ratio 0.5.
From above graphs it is clear that, for minimum tolerance, higher pressure
values are obtained compared to maximum tolerances.
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5 Product Development
Product development as described by Broman G, should be a coordinated
approach [1]. Starting with some assumptions and taking all constrains into
consideration, a theoretical modeling is developed. Upon further
investigation and simulation the model is optimized and final product
developed.
5.1 Design Approach
The aim is to design a test-rig to study the characteristics of the journal
bearing. The setup requires parts like shaft, sleeve and frame to be designed
and demands parts like motor of 1500 RPM with 0.5-1.5 Hp, plumber block
(2 Numbers) and plastic tubes to be procured from manufacturing
companies. These parts should be put together in an assembly for the rig.
The justification for the design of the parts and their assemblies are
explained in three different phases.
5.1.1 Phase 1
Initially the shaft and sleeve should be designed and the shaft is placed
inside the sleeve. The sleeve in the bearing is provide with holes on the
surface to allow the flow of lubricant through them due to the pressure
created in the bearing under running condition. The power to the shaft is
transferred from the motor. The shaft of the motor and the shaft of the
bearing are connected using flange coupling transmitting motion. From the
sleeve a weight hanger should be attached to apply load in the bearing.
5.1.2 Phase 2
The whole setup in phase 1 should be mounted on a flat surface a steel plate
of 7mm thick so there won’t be any miss alignment in the shaft and sleeve.
A weight hanger is attached to the sleeve. A frame is made so that this flat
surface can be mounted upon the frame. The frame should be rigid so that it
doesn’t deform when the load is applied. Also the top surface of the frame
where the bearing and motor setup is mounted should be flat with slightly
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high tolerance. This flatness allows the narrow alignment of the bearing
shaft and the motor shaft. The Frame will have an extension on one side in
order to mount the oil tank.
5.1.3 Phase 3
An oil tank is placed above the frame extension to supply lubricant to the
journal bearing. The tube from oil tank supplying lubricant is inserted in a
hole drilled in the sleeve especially for this purpose. The tank is placed
above certain height to the bearing, allowing constant flow of lubricant into
the bearing and providing sufficient inlet pressure in the bearing. Plastic
tubes of cylindrical cross section approximately 10 mm diameter and of
length approximate to the height of the wall are inserted into holes in the
sleeve and mounted straight along the height of the wall. When the bearing
is in running condition, due to the application of load by adding weight to
the holder, pressure develops in the bearing. The pressure in the bearing
forces the lubricant out of the sleeve holes and through the tubes attached to
them. Due to variations of pressure in the bearing, tubes in holes along the
surface of the sleeve will have different heights of lubricant level,
portraying the pressure distribution in the bearing.
5.2 Manufacturing parts
The manufacturing components are frame, shaft, weight holder, measuring
panel, base plate, adjustable pads. These parts are mostly manufactured by
mild steel except the sleeve, since sleeve should be made out of higher
strength material.
5.3 Parts to be procured
While building any equipment as known some parts have to be
manufactured and other parts can be procured, finally all the parts are
assembled together to form the equipment. Here in this section a list of all
the part required for this setup is made in two categories namely
procurement parts and the manufacturing parts.
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5.3.1 Procurement parts
Table 5.1. Parts to be procured.
Parts Description
1
Motor: To drive the shaft at a
uniform speed. Importance should be
given to torque requirement
2
Coupling: To connect the shaft and
the motor, a slight miss alignment
should be composited by the
coupling
3
Plumber block: To hold the shaft at
the two ends, alignment of the shaft
is of high importance
4
Pipes: For the easy flow of the
lubricant from the tank to the bearing
and also from bearing to the
measuring panel.
5
Weights: To be used to develop
pressure in the bearing.
6
Oil tank: To store lubricant and
supply and for the continuous supply
of lubricant.
7
Bolts and Nuts:
Are used to fasten the some
manufacturing parts and also secure
the bearing units.
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6 Design of individual parts
6.1 Bearing
6.1.1 Design need
The sleeve or bearing is an important part of journal bearing. The bearing
allows the rotation of shaft along a fixed axis without affecting the
efficiency of the transmission. This can be achieved by using lubricants
between the shaft and the sleeve. In our design the load in the bearing
which is a single piece component, is applied perpendicular to the rotating
axis. In this design, according to the requirement, the sleeve should be
capable of allowing the lubricant in continuously and pumping them out
when there is a pressure build up. The inner surface of the bearing should
be smooth without any deflection in the roundness, since uneven surface
may damage the shaft and the sleeve while applying load. The sleeve
should also hold the weight hanger where the load in the bearing is applied.
6.1.2 Dimension and specification
Table 6.1. Dimension and Specification for bearing.
Material Mild steel
Length of the bearing 100 mm
Inner diameter 100 mm
Outer diameter 122 mm
Number of holes 30
Holes outer diameter 9 mm
Holes inner diameter 1 mm
Bolt groove diameter 6 mm
Distance between grooves 60 mm
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6.1.3 Design motivation
The sleeve is strong enough to withstand load and should not deflect or
deform while applying the load. So the bearing is made of mild steel. The
inner surface of the bearing is well polished and the tolerance is very high
so that the shaft and sleeve won’t get damaged while applying load. This
also prevents the uneven distribution of pressure inside the bearing. The
fluid should flow out of the bearing to the pipes to depict the distribution of
pressure inside the bearing, so holes are drilled on even intervals to allow
the flow of lubricant outside the bearing. There are totally thirty holes
drilled throughout the bearing surface. The pressure will be high on the top
of the bearing, since the load is applied downwards. On the top layer of the
bearing there are twenty five holes drilled with five rows and five columns
and five rows with one column on the bottom surface. The plastic tubes
which allow the lubricant to pass through from the bearing are not directly
fixed to the bearing. Instead they are attached to small copper tubes fixed to
the bearing so that the tubes can easily be inserted and removed when
necessary. The weight hanger is attached to the bearing to apply load. The
weight hanger is therefore fastened to the bottom surface of the bearing.
Figure 6.1. Bearing.
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6.2 Journal shaft
6.2.1 Design need
Shafts are a mode of power transmission in any automobile application.
The shaft generally connects the engine and the drive. The shaft should be
made of strong materials so that it won’t deform under heavy loads and
high pressure. The shaft transmits power only in desired direction without
deviating from its path and it should be placed in between bearing sleeve.
The surface of the shaft should be very smooth because uneven surface
leads to irregular distribution of pressure and also leads to misalignment of
the shaft to that of the motor. The shaft should be connected to the motor
shaft using coupling. The coupling should be flexible so that slight
difference in shafts linearity can be adjusted. Key slot should be provided
in the shaft for coupling. Also the bearing shaft end and motor shaft end
should be of same diameter. Slots should be provided to constrain the axial
motion of shaft allowing it to have only single degree of freedom.
6.2.2 Dimension and specification
Table 6.2. Shaft Dimension and Specification.
Material Mild steel
Length of the Shaft 285 mm
Diameter 100 mm
6.2.3 Design motivation
The material used for making the shaft should be very hard and it should
not deform under heavy loads and high pressure, so mild steel is used for
making the shaft. The surface of the shaft is polished and is machined with
very high tolerance so that there won’t be any damage to the sleeve and
shaft also preventing the uneven distribution of pressure inside the bearing.
24
Circularity and roundedness are also very important while machining the
shaft. The shaft is hold by plumber blocks on each side. The diameter of the
shaft held inside the plumber block is small to restrict the movement of the
shaft axially, so that the shaft rotates in a confined path. At one end of the
shaft is provided with a sir clip to hold the shaft inside the plumber block
from moving out. The rear end of the shaft connecting the motor is still
reduced in diameter to match the coupling diameter, which connects with
the motor. A keyway is provided at the end of the shaft to connect with the
coupling. The coupling used for connecting the journal shaft and the motor
shaft is Oldham coupling since it is flexible and slight misalignment in the
linearity of both the shafts can be adjusted.
Figure 6.2. Journal Shaft.
6.3 Base plate
6.3.1 Design need
The base plate is placed above the table frame where the journal bearing
setup and motor are fixed. The base plate is rigid enough so that it won’t
undergo any deflection while applying the load. Since the motor and
bearing are mounted on the same surface, the surface flatness of the plate is
very high preventing any misalignment between the bearing shaft and the
25
motor shaft. The base should also provide certain space for the weight
hanger to hang down freely.
6.3.2 Dimension and specification
Table 6.3. Base plate dimension and specification.
Length 800 mm
Breadth 300 mm
Thickness 7mm
Bolt groove diameter M16
Length (hollow section) 150 mm
Breadth (hollow section) 120 mm
Material used mild steel
Section solid
6.3.3 Design motivation
The base plate is made of mild steel for good tensile strength and rigidity.
The suitable thickness of the base plate for maintaining good strength is 7
mm, which will provide a rigid platform for the motor and bearing setup
won’t deform under high loads. The plate is attached to the table frame
using bolts so that the whole experimental setup can be easily dismantled
and assembled. The plate should be flat in order to prevent misalignment of
the shafts. So the tolerance in flatness is set to 0.01-0.00 which is very
suitable for the type of flatness expected. The bearing and shaft are held by
two plumber blocks, which are fastened to the base plate using bolts. The
bolt grooves to fix the plumber block are extended horizontally on the top
26
and vertically at the bottom to adjust the journal bearing’s linearity with
respect to the axis of shaft and motor. In between the two plumber blocks a
hollow section is made to allow the weight hanger, which is attached to the
bearing sleeve to hang down freely. The base plate is cut into a hollow
section at a distance of 200 mm from the plate’s end.
Figure 6.3. Base plate.
6.4 Frame
6.4.1 Design need
The basic need of the design is to hold the whole bearing setup providing a
rigid platform. The table is made compact and portable so that it can be
easily transported and installed in laboratories. The table is sturdy enough
in order to absorb vibrations of motor and bearing in running condition.
The table is rigid so that it will not deform in shape during application of
load in the bearing. This is a main factor to be considered because
deformation in the table leads to misalignment and linearity between the
bearing shaft and motor shaft leading to damage of the journal bearing. The
table should be designed also to hold the oil tank at certain height above the
bearing setup for providing continuous lubrication to the bearing.
27
6.4.2 Dimension and specification
Table 6.4. Frame Dimension and Specification.
Length 800 mm
Breadth 600 mm
Height 500 mm till the base plate
300 mm above base plate to hold
the oil tank
Material used Mild steel
Section Square hollow section of side
40*40 mm and 2 mm thickness
6.4.3 Design motivation
The material used for manufacturing the table is mild steel since it will be
strong and provide a rigid platform that won’t deform under heavy loads. A
solid section of mild steel throughout the table will make the table too
heavy which affects the mobility of the table. This can be overcome by
using hollow sections of mild steel throughout the frame. This makes the
frame strong and less weight comparatively. The oil tank in this setup will
be helpful if it is placed somewhere closer to the table. So we planned for
the oil tank holder fixed to the table. So from the one side of the table an
extension of the frame is designed above to hold the oil tank. All the joints
in the frame are welded. The legs of the table are provided with leveling
pads in order to ensure that the table on uneven surface is balanced. Also
these pads will prevent the surface under the table from damaging.
28
Figure 1.4. Frame.
Figure 6.5. Leveling pads.
29
6.5 Weight holder
6.5.1 Design need
The purpose of this component is to hold the weights added to the bearing
to create the necessary pressure in the bearing. The holder is fastened with
the help of bolts to the bottom surface of the bearing sleeve. The holder
should be designed with less weight material so that its load impact on the
bearing will be negligible. A projection is made in the base plate to allow
the weight holder hang freely downwards without any hindrances. Also the
weights can be easily added and removed from the holder.
Figure 6.6. Weight holder.
6.6 Copper tubes
6.6.1 Design need
When the bearing is in running condition there will be flow of lubricant
outside the holes in the bearing sleeve. This lubricant is collected in a tube
and mounted on the wall. The tube is not directly connected to the bearing.
These tubes can’t firmly fix to be bearing since the depth of the hole is very
less. Instead we can fix a copper tube of the same diameter of the bearing
holes to the sleeve and in turn the tubes collecting lubricant can be fixed to
them so that they can be held firmly while the fluid is pumped out. For this
design we can procure a long copper tube of required diameter and
thickness and can be cut into small pieces.
30
6.6.2 Dimension and specification
Table 6.5. Copper tube Dimension and Specification.
Material Copper
Length 30 mm
Diameter 9 mm
Thickness 1 mm
Figure 6.7. Copper tube.
6.7 Oil tank
This component is not necessarily to be manufactured. A readily available
plastic tank can also be sued for the purpose. The main function is to hold
the oil and give a continuous supply of the lubricant while testing.
31
7 Assembly process
The assembly of the whole setup is described by the assembly diagram
drawn in Auto-CAD and a stepwise assembly diagram using Photoshop.
Figure7.1. Assembly 1.
Figure7.2. Assembly 2.
32
Figure7.3. Assembly steps.
33
7.1 Assembly chart
PHASE 1 PHASE 2 PHASE 3 PHASE 4
FRAME FIXED
WITH LEVELING
PADS AT THE
BOTTOM
BASE PLATE
SHOULD BE
PLACED ABOVE
THE FRAME
BASE PLATE IS
FASTENED TO THE
FRAME USING
BOLTS
PLUMBER BLOCK 1
IS FIXED TO THE
BASE PLATE USING
SUPPORT BLOCK
SHAFT INSIDE THE
BEARING,
ATTACHED WITH
WEIGHT HANGER IS
PLACED INSIDE
PLUMBER BLOCK 1
PLUMBER BLOCK 2 IS
PLACED ON THE OTHER
SIDE OF THE BEARING
AND FASTENED TO THE
BASE PLATE ARRESTING
THE BEARING HUS
SHAFT IS
CONNECTED TO
THE COUPLING
OTHER END OF
THE COUPLING IS
CONNECTED TO
THE MOTOR
SHAFT
MOTOR IS
FASTED TO THE
BASE PLATE
USING BOLTS
OIL TANK IS
PLACED ABOVE
THE FRAME
TUBES MOUNTED
ON THE WALL
CONNECTED TO THE
BEARING SLEEVE
OIL COLLECTING PAN
SHOULD BE PLACED
BELOW THE BEARING
HUS TO COLLECT THE
LEAKING OIL
34
7.2 Assembly Steps
Frame connected to leveling pads are placed first.
Base plate should be placed on the frame.
Plumber block 1 fastened to the base plate.
Bearing sleeve with shaft is connected to the plumber block 1.
Plumber block 2 is fastened to the base plate holding the bearing
and shaft.
Weight holder is connected to the bearing sleeve.
Coupling is made between bearing shaft and motor shaft.
Motor is fastened to the base plate.
Oil tank is placed above the frame.
Copper tubes are connected to the bearing sleeve.
Tubes for collecting oil are connected to the copper tubes.
Oil collecting pan is placed below the bearing setup.
35
8 Experimental approach
Figure 8.1. Experimental approach flow chart.
8.1 Working principle
Oil tank at certain height creates a pressure head, which helps in
easy moment of lubricant into the bearings.
Due to rotation of the shaft and load on the sleeve, a load bearing
pressure is created.
In the region of load bearing pressure, the lubricant is pumped out
through the holes provided on the sleeve.
The oil from these holes is made to pass though tubes to the
measuring panel.
The difference in height of the inlet and outlet pressure heads helps
us in calculating the pressure at the specific point on the sleeve.
36
The obtained pressure vales are tabulated to get the pressure
distribution in the journal bearings
8.2 Calculation of pressure head
Pressure head at inlet and outlet can be calculated using the following
formulas.
Inlet pressure
Pi = -γ * H1 (8.1)
Specific weight
γ = ρ * g (8.2)
Outlet pressure
Po = Pi – γ * (H2-H1) (8.3)
37
9 Cost Estimation
Costing is the initial approximation of the budget requirements to
manufacture the product. It plays an important role in decision making. The
costing of the present product was done based on the current market prices
of the material and a rough estimate of the total cost is made, taking into
consideration, both the material as well as labor cost.
The costing model was arrived at after a good study of different suppliers,
manufactures for each product and a visit to a small scale industry in
Karlskrona. Discussion with people from this industry helped us in
understanding the different aspect involved such as machining time and
labor requirement for producing some of the parts. The table below lists out
the cost required for each item available in market.
Table 8.1. Estimated Cost of the whole Setup.
Item Functionality Quantity Price
per unit
Total
price
1 Motor To drive the journal and
create the required torque
to build up the pressure.
1
1594
1594
2 Bearing
unit
Used to support the
journal shaft at the ends.
2 225 450
3 Frame Made of hollow mild
steel tubes to support the
whole equipment.
1.5*20ft
249 for
4
meters
1245
4 Steel plate To form a base on the
frame to support the
motor and journal bearing
assemble.
1/4ʺ
2*2 ft &
3/8ʺ
1*2
581
38
5 Steel
support
block
To form a base on the
steel plate and to support
the plumber block.
0.105ʺ
2*2 ft
217
6 Adjustable
pads
To be fixed at the bottom
of the frame to act as anti
vibrant
4
26.5
106
7 Hydraulic
hose
For the oil to flow form
bearing to measuring
panel.
9mm
thick
50metes
3174
8 Coupling To connect with shaft and
motor , also to the care of
any miss alignment
1
505
505
9 Copper
tubes
To fix the tubes to the
bearing
3ft 44.73
Based on feedback received from the industry and study of cost form
different supplier, a final estimate of the test rig has been made. As
estimated a total of 20000kr would be required to produce this equipment
including material, machine time and labor cost.
39
10 Conclusion
This thesaurus mainly concentrates on design of a test rig, which will help
in study of the characteristics of journal bearing including load bearing
capacity, maximum pressure and material selection. The whole setup is
designed using AutoCAD inventor. Simulations were done in the same
software for checking the maximum stress and the design was altered in
order to prevent deformation while applying the load. The design is made
as compact as possible after a lot of brainstorming and design motivations
for every part are mentioned in the present report. An approximate cost of
producing the whole setup after consulting a manufacturing company in
Karlskrona has been made. The cost of the components that are to be
manufactured and the cost of the components to be procured are tabulated.
Initially analytical results are calculated for pressure distribution with
necessary assumptions regarding dimensions and load. Once the setup is
manufactured and in running condition, the pressure distribution of the
bearing should be experimentally calculated and compared with the
analytical results. This design will help the reader to visualize the behavior
of the journal bearing under varying loads.
40
11 Future work
The behavior of this design is not visualized by the present work and the
experimental results were not calculated since the product is not
manufactured yet. After the test rig is manufactured, an experiment should
be conducted and its characteristics should be studied. If there is any
drawback in the present design that is noticed while the bearing is in
running condition, those things needs to be altered. Once the experimental
results are obtained it should be compared with the analytical results and a
motivation of the results should be portrayed.
41
12 References
1. Broman. G, (2003), Computational Engineering, Department of
Mechanical Engineering, Blekinge Institute of Technology, Karlskrona,
Sweden.
2. Stolarski. T. A, (), Tribology in Machine Design.
3. John Williams, (2005), Engineering Tribology, Department of
Engineering, University of Cambridge, London.
4. Antti Vilkonen, (2009), Oil Film Pressure in hydrodynamic journal
bearing, Department of Engineering Design and Production, Helsinki
University of Technology, Finland, ISBN 978-952-248-162-7.
5. James Carvill, (1993), Mechanical Engineering Data handbook, ISBN
0-7506-1960-0.
6. Francis X. Dobler, (1965), Development of pivoted pad Journal bearing
for potassium lubricated space electric power generator.
7. Yang Lihua, HU deyi, Liu Heng, Yu lie, (2008), Experimental
investigation and performance of aero dynamic compliant foil Air
bearings, Proceeding of IEEE, International conference on Automation
and Logistics.
8. Avraham Har noy, bearing design in machinery, Engineering Tribology
and lubrication.
9. Description of Fits/Graphical Representation of Standard fits, Tolerance
table for regularly used fits, (1999), Expert from JIS-B-0401.
42
10. Qiang LI, Shu-Lian, Xio-Hong, Shui-Ying, (2011), A new method for
studying the 3D transient flow of misaligned journal bearing in fixed
rotor bearing system, ISSN 1673-565X.
11. Metal Work Pneumatic, General Catalogue.
12. SKF general catalogue.
13. Misumi Europa GmbH, General Catalogue.
14. Muller industries, General Catalogue.
15. Hahn Und Kolb, General Catalogue.
16. http://www.substech.com/dokuwiki/doku.php?id=hydrodynamic_journa
l_bearing
17. http://en.wikipedia.org/wiki/Coupling
18. http://www.oepcouplings.com/content/oldham_couplings/oldham_coup
lings.asp
19. http://www.brighthubengineering.com/machine-design/43237-shaft-
couplings-types/
20. http://www.rowland2.com/pdfs/lovejoy/SierBath.pdf
21. http://www.gkmpower.com/ABB_MOTORS_PRICE_LIST.pdf
22. http://www.metalsdepot.com/catalog_cart_view.php?msg=
43
23. http://www.metals4u.co.uk/
24. http://www.engineeringtoolbox.com/static-pressure-head-d_610.html
44
Appendix
Bearing
45
Shaft
46
Weight holder
47
Assembly
48
Support block
49
Frame 1
50
Frame 2
School of Engineering, Department of Mechanical Engineering Blekinge Institute of Technology SE-371 79 Karlskrona, SWEDEN
Telephone: E-mail:
+46 455-38 50 00 [email protected]